Hot box detector structures for railways

ABSTRACT

The hot box detector structure comprises a main enclosure and an upper deck enclosure. The main enclosure houses the radiometer which should be maintained at ambient temperature. For this reason, the upper deck enclosure is separated from the main enclosure by a suitable air space. It also supports a surrounding sun shade to further protect the main enclosure of the structure from the direct rays of the sun and thus prevent the building up of its internal temperature above the ambient. The tower enclosure rises from one end of the main enclosure and includes a window at its top or head through which the radiometer can view the passing hot elements of a moving train. The head of such tower also includes certain operative parts such as a shutter for the window, heating elements, shutter control, window washer and dryer, and the like. This head of the tower is heat insulated from the tower supporting structure and from the main enclosure.



1. A hot box detector structure comprising, a main enclosure containing a radiometer, a tower connected to said main enclosure by a heat insulating material, said tower having a window at its upper end through which said radiometer can view and provide a responsive output to passing hot elements, an electric heater element disposed in the upper part of said tower operative when energized for heating said window and preventing frosting of the window, whereby the main enclosure is substantially unaffected by the heating of the window due to the presence of the insulating body.
 2. The structure as specified in claim 1 including a dock enclosure mounted over said main enclosure with an intervening air space, overhanging said main enclosure, and a sun shield substantially surrounding said deck enclosure.
 3. A structure as specified in claim 1 wherein a normally closed mechanical shutter is located above said window capable of being actuated to an open position, said shutter being reflective on its lower surface, and wherein said radiometer is provided with a test target so located as to be reflected by said lower surface of said shutter into said radiometer and having a viewing path substantially the same length as the path provided for viewing passing hot train elements, whereby said test path also includes said window with its then existing degree of transparence.
 4. A hot box detector structure comprising: a main enclosure for containing a radiometer, a tower insulatively connected at its lower end to said main enclosure and having a window at its upper end through which said radiometer can view passing of hot elements, a shutter above said window capable of being operated to an open position, an electric heater element substantially surrounding said window in the upper part of said tower, and thermostatic control for said heater element to maintain a temperature above freezing whereby said shutter and said window are prevented from becoming frosted and accumulating snow, and said tower and main enclosure are isolated by said insulative attachment for preventing the heater from affecting the operability of the radiometer.
 5. A structure as specified in claim 4 wherein a cover plate is mounted over said shutter but allowing free movement thereof, said cover plate also having an opening substantially opposite said window.
 6. A structure as specified in claim 4 wherein a shroud is mounted over said shutter but without materially obscuring said window and permitting the free movement of said shutter.
 7. A hot box detector structure as specified in claim 1 wherein means is provided for spraying said window with fluid, and wherein additional means is provided for flowing air across said window for a limited time following said spraying action.
 8. A structure as specified in claim 7 wherein said window spraying means is effective upon a departure of a train but before said shutter is closed.
 9. A structure as specified in claim 8 wherein said air blowing means stops blowing air concurrent with the closure of said shutter.
 10. A hot box detector structure including a window through which a radiometer can view passing hot train elements comprising, a source of compressed air, means for connecting said source of air to a nozzle adjacent said window through a normally closed control valve, means rendered effective upon the passage of a train for intermittently actuatinG said valve to release blasts of air across the face of said window, a source of fluid under pressure located adjacent said detector structure, means connecting said source of fluid to a nozzle adjacent said window through a normally closed control valve, and means rendered effective upon the passage of a train out of the section adjacent said detector structure for momentarily actuating said fluid control valve for releasing a limited quantity of fluid just prior to the last blast of air across said window.
 11. A hot box detector structure including a window through which a radiometer can view passing hot train elements comprising, a source of compressed air located adjacent to said hot box detector structure, means for connecting said source of air through a nozzle adjacent said window and also through a normally closed control valve, and means rendered effective upon the passage of a train for actuating said control valve to release a blast of air across the face of said window, a source of fluid under pressure located adjacent said structure, means connecting said source of fluid to a nozzle adjacent said window through a normally closed control valve, means rendered effective upon the departure of said train for temporarily actuating said fluid control valve for releasing a limited quantity of fluid from said nozzle, said means also causing actuation of said air control valve for effecting a final blast of air across said window, and heater means located adjacent said window for maintaining the temperature thereof at a value above freezing. 